look at your keyboard. there is a scroll lock button.
press it. a green light will light up
but you will not feel a diference...
so what it does?
while the scrool lock is on, it will lock the HDD scrolling. so when you download stuff from the internetz, the directory will not scroll. forcing the computer to write to the oldest file in that page. this makes sure that no more space is used! the computer will overwrite the files from the beggining again
this is hdd recicling! why keep that obsolente 10 years old file when you can use that space for a more recent file!